1. Field of the Invention
The present invention relates to an Electromagnetic Bandgap (EBG) structure, and more particularly, to an overlay Electromagnetic Bandgap (EBG) structure for reducing leakage loss of an electromagnetic wave through a substrate, and a method of manufacturing the same.
2. Description of the Related Art
With the development of information communication technologies, various communication devices have been developed and distributed. Also, to increase the number of communication channels and reduce the size of communication systems, various communication devices using high-band frequencies are being developed. Such communication devices essentially have a function of selecting or controlling a specific frequency. In general, a circuit for selecting or controlling a specific frequency is implemented by arranging lumped-type passive elements (for example, inductors or capacitors).
However, when a high frequency is used, a wavelength is shortened, and accordingly interference between communication lines becomes significant, so that each communication line operates as a circuit element. That is, since the number of unexpected components increase in a high frequency environment, a problem may occur when general passive elements are used in a microwave band (or in a millimeter wave band).
For this reason, research into developing passive elements capable of being used in a super high frequency band has been carried out. For example, a trial has been conducted to arrange existing lumped elements on the same plane to predict parasitic components in a high frequency environment. A remarkable structure is an electromagnetic bandgap (EBG) structure in which a photonic bandgap (PBG) structure for guiding photons is applied to a super high frequency area. The EBG structure is applied to various devices, such as a filter, a resonator, etc.
However, an existing EBG structure causes additional leakage loss of an electromagnetic wave through a substrate when a PBG is integrated into a flat integrated circuit, and the leakage loss deteriorates a band selection characteristic of a filter.